Seasonal and within-stem variations of neutral lipids in silver birch (Betula pendula) wood.

摘要: Neutral lipids were analyzed in stem wood of a 7-year-old clone and five 35-70-year-old mature trees silver birch (Betula pendula Roth). In young old trees, the free fatty acid fraction comprised less than 5% concentration triacylglycerols (TG). The linoleic was lowest March when dormant highest during midsummer September. TG increased toward pith, indicating that living parenchyma cells close to pith have large storage capacity. (mean 0.51 +/- 0.02% dry mass) remained constant throughout year whereas beta-sitosterol, dominant sterol 82.5 0.4% total sterols), decreased spring early summer temperature gradually increased, autumn became dormant. we detected seasonal interconversion between esterified forms beta-sitosterol campesterol, within steryl ester squalene betulaprenol-7. sterols/isoprenoids exceptionally high, especially inner regions 0.6 0.03% mass). No heartwood formation detected.